The present invention relates to a receiving apparatus and a transmitting apparatus which are suitable for a broadcast system, and to a communication system comprising the receiving apparatus and the transmitting apparatus.
In a conventional broadcast system which is one of a communication systems, an attention has been focused on a fact that a radio broadcasting wave has an eclipsing (or blanking) period and based on this eclipsing period, data or information has been inserted into the eclipsing period. In this method, in addition to primary data representing dynamic image (foreground image) by the radio broadcasting wave and a voice, subsidiary data representing a static image (background image) can also be transmitted to the receiving apparatus. Accordingly, the receiving apparatus permits to reproduce the dynamic image and voice or sound in accordance with the primary data and, in addition, static image and voice or sound in accordance with the subsidiary data.
In the method of superimposing the data in the eclipsing (blanking) period of the radio broadcasting wave, there is a problem that it is not possible to transmit the data which commands different processing relative to the same and equal image. In other words, the data is superimposed in the eclipsing period and, therefore, there is only one command for processing relative to the image.
Besides, in terms of copyright protection and enforcement in these days, an attempt has been made to insert an electronic watermark into a given image as suggested by, for example, Japanese Unexamined Patent Publication (JP-A) No. 9-191394. The watermark is realized by inserting specified data into the intended image. In this case, the image into which the watermark is inserted is almost equivalent to the other image having no watermark inserted thereinto to human eyes and the inserted watermark is not recognized visually. Further, a watermark insertion technique as described above permits prevention of unauthorized or uncertified utilization of image, as shown in Japanese Unexamined Patent Publication (JP-A) No. 7-212712.
It is therefore an object of the present invention to provide a new receiving apparatus which permits to command a plurality of processes simultaneously relative to the image, by utilizing the watermark insertion technique.
It is another object of the present invention to provide a communication system comprising the receiving apparatus and a transmitting apparatus for transmitting an image datum to which a specified datum is inserted as a watermark.
It is still another object of the present invention to provide a transmitting apparatus included in the communication system.
Other objects of the present invention will become clear as the description proceeds.
According to a first aspect of the present invention, there is provided a receiving apparatus for use in reception of an image datum to which a specified datum is inserted as a watermark by a watermark insertion technique. The image datum represents an image. The specified datum represents a specified process for the receiving apparatus. The receiving apparatus comprises receiving means for receiving the image datum, producing means connected to the receiving means and responsive to the image data for producing the image, and processing means connected to the receiving means and responsive to the image datum for processing the specified datum to execute the specified process.
According to a second aspect of the invention, there is provided a communication system comprising the above-mentioned receiving apparatus and a transmitting apparatus for transmitting an image datum to which a specified datum is inserted as a watermark by a watermark insertion technique. The image datum represents an image. The specified datum represents a specified process for the receiving apparatus.
According to a third aspect of the invention, there is provided a transmitting apparatus for use in transmission of an image datum towards a receiving apparatus. The image datum represents an image. The transmitting apparatus comprises an insertion circuit for inserting a specified datum as a watermark into the image datum by a watermark insertion technique. The specified datum represents a specified process for the receiving apparatus. The transmitting apparatus further comprises transmission executing means connected to the insertion circuit for executing transmission of the image datum.